Question

THe enthalpy of neutralization of HCN (aq) with NaOH (aq) is -12.0 kJ/mol. Using your value for the enthalpy of neutralization of H+(aq) with OH-(aq) and the technique used in question 2, determine the enthalpy of ionization of HCN. Compare the relative amounts of ionization of HCL and HC2H3O2. Which is the stronger acid?

Question 2.

The neutralization of HC2H3O2 (aq) by NaOH(aq) (part C) can be considered to be the sum of the neutralization of H+(aq) by OH-(aq) (part B) and ionization of HC2H3O2 (HC2H3O2 -> H+ +C2H3O2-). Write the net ionic equation for each of these reactions and demonstrate how two of them add together to yield the third.

HCl = 21.1 C

NaOH = 21.4

Mix = 27.8

Answer 1

in general strong acid when react with strong base will form liquid water and salt . in this process. the enthalphy change -57.3 kJ / mol

H+ (aq) + OH- (aq) --------------------> H2O (l) , DH = -57.3 kJ/mol

HCN + NaOH ---------------------> NaCN + H2O , DH = - 12 kJ/ mol

enthalpy of ionisation of HCN = -12 - (-57.3) = 45.3 kJ / mol

so for HCN dissociation : 45.3 kJ / mol energy utilised. this is called enthalpy of ionisation of HCN.

enthalpy of ionisation   for HC2H3O2 = +1.2 kJ/mol

HCl is strong acid there is no need of enthalpy of dissociation of HCl.

so HCl is stronger acid than HC2H3O2

Question : B)

net ionic equation:

HC2H3O2 (aq) + OH - (aq) ----------------------------> C2H3O2- (aq) + H2O (l)